I don't tend to wear thicker socks with these boots because I don't generally stay outside that long. Boots in general tend to run a bit more roomy on the same Last however that may not be enough room that you can wear a thicker sock. Some retailers tend to stock the 64 in the F width specifically for this purpose. I would think a wider width same size might be a better choice.
I have galway in E and F width.
64 in F width works better for thicker socks than going up a 1/2 size. I also dont like when the shoes get too long in the toe (going up a size) and rather get a wider version.
The 64 in general is not that roomy IMO (my foot at least) and going up to a wide works well if you want thick socks